For using 3rd party Octavia providers (such as OVN provider) an
octavia-driver-agent container must be running to expose those providers to
use.

OVN CI job has been extended with deploying Octavia and testing OVN Load
Balancer.

Closes-Bug: #1903506
Depends-On: https://review.opendev.org/c/openstack/kolla/+/771191

Change-Id: Ibafa8b7307981f2a51e630cc113d18af6162171c

Fixes:
- SB/NB DB address format (single host) for SB/NB DB daemon
- SB/NB DB address format (all hosts) for Neutron / northd /
  ovn-ovs bootstrap
- OVN tests

Change-Id: I539773c48f89b731d068280c228ce11782bf5788
Closes-Bug: #1875222

Followup of last reviews from [1].

[1]: https://review.opendev.org/#/c/696841

Change-Id: I7085093b20e8848e09dc521ae9fbf120e909470d

Implement OVN Ansible role.

Implements: blueprint ovn-controller-neutron-ansible

Depends-On: https://review.opendev.org/713422
Change-Id: Icd425dea85d58db49c838839d8f0b864b4a89a78